Specification Part 3 - Road & Bridge Works - Urban Administration ...

(4) Rolling shall be discontinued when the aggregates are partially compacted with sufficient void space in them
to permit application of screenings.
(5) However, where screenings are not to be applied, as in the case of crushed aggregates like brick metal,
laterite and kankar, compaction shall be continued until the aggregates are thoroughly keyed.
(6) Curing rolling, slight sprinkling of water may be done, if necessary.
(7) Rolling shall not be done when the sub grade is soft or yielding or when it causes a wave- like motion in the
sub grade or sub base course.
(8) The rolled surface shall be checked transversely and longitudinally, with templates and any irregularities
corrected by loosening the surface, adding or removing necessary amount of aggregates and re -rolling until the
entire surface conforms to desired cross fail (camber) and grade. In no case shall the use of screenings be
permitted to make up depressions.
(9) Material which gets crushed excessively during compaction or becomes segregated shall be removed and
replaced with suitable aggregates.
(10) It shall be ensured that shoulders are built up simultaneously along with water bound macadam courses as
per Clause 407.4.1.
404.3.5. Application of screenings: (1) After the coarse aggregate has been rolled to Clause 404.3.4,
screenings to completely fill the interstices shall be applied gradually over the surface. These shall not be damp
or wet at the time of application.
(2) Dry rolling shall be done while the screenings are being spread so that vibrations of the roller ca use them to
settle into the voids of the coarse aggregate.
(3) The screenings shall spread uniformly in successive thin layers either by the spreading .motions of hand
shovels or by mechanical spreaders, or by any other machine so that the course aggregate shall not be
disturbed.
(4) The screenings shall be applied at a slow and uniform rate (in three or more applications) so as to ensure
filling of all voids. This shall be accompanied by dry rolling and brooming with mechanical brooms, hand brooms
or both.
(5) In no case shall the screenings be applied as fast and thick as to form cakes or ridges on the surface in such
a manner as would prevent filling of voids or prevent the direct bearing of the roller on the coarse aggregate.
(6) These operations shall continue until no more screenings can be forced into the voids of the coarse
aggregate.
(7) The spreading, rolling, and brooming of screenings shall be carried out in only such lengths of the road
which could be completed within one day’s operation.
404.3.6. Sprinkling and grouting: After the screenings and rolling the surface shall be copiously sprinkled with
water, swept and rolled.
(2) Hand brooms shall be used to sweep the wet screenings into voids and to distribute them evenly.
(3) The sprinkling, sweeping and rolling operation shall be continued, and additional screenings apply where
necessary until the coarse aggregates are well bonded and firmly set for the entire depth and until a grout has
been formed of screenings and water that will fill all void and formed a wave of grout a head of the wheel to the
roller.